So? What's the problem with it using timer0?
A couple of things : instead of ON for 6 minutes then off, I want ON for 6 hours. But it doesn't have to be accurate. 1/2 hour each side will be fine. Will using millis() still work ?
The other thing is, I am trying to really get the power consumption down (when the LED is OFF) by turning the ADC off, and using Power Down. Will my interrupt bring me out of power down ?
When the INT0 interrupt is enabled and is configured aslevel triggered, the interrupt will trigger as long as the pin is held low.